1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to a data transmission, and more particularly, to a data transmission method and apparatus in a communication environment in which network and/or hardware characteristics are changed.
2. Description of the Related Art
Accompanying the development of communication technology, various kinds of wired/wireless communication services and associated communication standards, which support multimedia communication, exist. In particular, increases in data rates have resulted in an increase of real-time audio and video streaming services through wired/wireless communication. For real-time streaming services, a technique enabling a user to listen to the music or view video in a seamless manner is most important. In particular, when a communication environment is changed, the importance of a data transmission method for seamless communication between a sender and a receiver is emphasized.
FIG. 1 illustrates a case of data communication in which a communication environment is degraded during data transmission.
In FIG. 1, it is assumed that a mobile terminal of a receiver 11 moves from a Wireless Local Area Network (WLAN) network 130 having a maximum data rate of 2 Mbps to a Wideband Code Division Multiple Access (WCDMA) network 140 having a maximum data rate of 384 Kbps. A sender 12 in a 2 Mbps wireless communication network is transmitting data to the mobile terminal of the receiver 11 at a data rate of 1 Mbps in operation 101 and does not know the characteristics of a network to which the mobile terminal of the receiver 11 moves. Thus, if the sender 12 continuously transmits data to the mobile terminal of the receiver 11 at the same data rate in operation 103 after handover of the mobile terminal of the receiver 11 is accomplished in operation 102, the mobile terminal of the receiver 11 cannot receive all data transmitted by the sender 12. That is, a data loss occurs. Thus, if the data being transmitted is streaming data, such as music or video, the receiver 11 cannot seamlessly listen to the music or view the video in real-time.
FIG. 2 illustrates a case of data communication in which a communication environment is improved during data transmission.
In FIG. 2, it is assumed that a mobile terminal of a receiver 21 moves from a WCDMA network 230 having a maximum data rate of 384 Kbps to a WLAN network 240 having a maximum data rate of 2 Mbps. A sender 22 is transmitting data to the receiver 21 at a data rate of 384 Kbps in operation 201 before handover of the mobile terminal of the receiver 21 and does not know the characteristics of a network to which the mobile terminal of the receiver 21 moves. Thus, if the sender 22 continuously transmits data to the mobile terminal of the receiver 21 at the same data rate in operation 203 after the handover of the mobile terminal of the receiver 21 is accomplished in operation 202, data transmission is inefficient since the data is transmitted at the data rate of 384 Kbps in the WLAN network 240 having the data rate of maximum 2 Mbps.
Data loss or inefficiency of data transmission may occur in a case of not only the handover between heterogeneous networks illustrated in FIGS. 1 and 2 but also handover between homogeneous networks. In addition, when network characteristics of the same network is changed without a handover, data loss or inefficiency of data transmission may also occur.
Besides the network characteristic information, hardware characteristic information of a sender and/or a receiver may also affect data communication. If the sender continuously transmits data without considering that a mobile terminal of the receiver cannot process data due to a change in an available resource of hardware such as Central Processing Unit (CPU) or memory, the mobile terminal of the receiver cannot receive the data normally.